The call for Congressman Ryan of Wisconsin – the young Budget Committee chairman dubbed the intellectual leader of the GOP – has more backers, including The Wall Street Journal editorial page and top editors at The Weekly Standard. The chattering classes treat Governor Christie of New Jersey, floated for vice president by Washington Post columnist Michael Gerson, as a less serious possibility, given his blunt style, big persona, and short time in office.

But the larger point is this: The conventional wisdom that Mr. Romney will play it safe, and choose between Senator Portman of Ohio and former Governor Pawlenty, has sparked worry among some leading Republicans.

Why? Just look at the polls. Romney, the presumptive Republican presidential nominee, is clearly trailing President Obama, and conservatives are worried that loyal but bland understudies won’t help give Romney’s candidacy the juice it apparently needs. The most recent polls, CNN/Opinion Research and Fox News, have Obama up by seven and nine percentage points, respectively.

In their Weekly Standard piece, Stephen Hayes and William Kristol tackle the argument that “the Ryan budget” – a bold, controversial blueprint for spending cuts and entitlement reforms – makes the congressman a risky choice. Romney embraced the Ryan plan during the primaries, and will continue to campaign on it, they say, so why not have its author out there making the case himself?

“Having Paul Ryan on the ticket may well make it easier to defend the plan convincingly,” Messrs. Hayes and Kristol write. “Ryan's pretty good at that.”

The Wall Street Journal editorial argues that Americans are hungry for a leader willing to take on tough issues – and that the choice of Ryan would reinforce that message.

“Whatever doubts Americans may have about Mr. Romney's empathy or background, more of them will turn out for him if they see a leader with a vision and plan worthy of the current difficult moment,” the Journal editorial says.

The case for Christie may be a tougher sell for some conservatives. While Ryan has been in Congress since 1999, despite his tender age (early 40s), Christie has been governor for just 2-1/2 years and has no Washington experience to flesh out Romney’s own lack of Washington service. More potentially problematic is Christie’s penchant for dressing down voters in public. The clashes make for entertaining YouTube videos, and he is reasonably popular in his Democratic home state, but his Jersey style may not wear well day in and day out on the stump.

Mr. Gerson says that Christie’s combativeness, in fact, is exactly what Romney needs, in a campaign that has become a “vicious, negative slugfest.”

“Romney needs more than an appealing spokesman,” Gerson writes. “He needs someone to engage aggressively on his behalf in the daily D-Day this campaign has become. All four leading vice presidential prospects might play this role. Christie would clearly play it best.”

Christie is also rumored to be the likely convention keynote speaker, which would take him out of the running for veep.

In any event, since Gerson’s blog post floating Christie for veep went up Thursday afternoon, there hasn’t exactly been a stampede to his point of view.

The Ryan idea seems to have more traction. In an interview with NBC on Thursday, Romney said he wants a running mate with “a vision for the country that adds something to the political discourse about the direction of the country.”

Democrats, meanwhile, are salivating over Ryan as the veep choice. His plan to turn Medicare into a voucher-like system led to a memorable ad showing a Ryan look-alike pushing Grandma in her wheelchair off a cliff. That ad, and many more like it, would surely come back.

In addition, putting Ryan on the ticket would center the focus of the Romney campaign on the nation’s unsustainable fiscal path – to be sure, a concern of voters – and away from job creation and the economy, the No. 1 issue. Ryan’s youth could also give voters pause.

Portman and Pawlenty also contain risks. Portman was budget director in the George W. BushWhite House, a negative for conservatives. Pawlenty was a two-term governor of a blue state, which also gives some conservatives pause. Both men have a nice-guy demeanor, which could make either of them less-than-convincing as an attack dog, a key role for the running mate.

In the end, only one thing is certain: We’ll get the answer soon. The Republican convention starts in 17 days.